Microsoft CEO Steve Ballmer speaks during the press conference of the Finnish mobile manufacturer Nokia in Espoo, Finland on Tuesday, Sept. 3, 2013. Microsoft has announced Tuesday a takeover of the Finnish mobile phone company in a deal reported to be worth some $7.2 billion.
(Markku Ulander/AP photo/LEHTIKUVA)

Microsoft's decision to acquire Nokia's phone and services business for $7.28 billion is a very bold bet. It may be one of the last hurrahs for outgoing CEO Steve Ballmer.

Nokia has long been Microsoft's closest partner when it comes to its Windows Phone operating system. Nokia's CEO Stephen Elop, a former Microsoft employee, bet the company on Windows by making it the exclusive operating system for its latest smartphones. With this acquisition, the bet paid off, at least in the short term. And it could pay off even further for Elop if, as rumor has it, he winds up replacing Ballmer as CEO. But the long-term success of the Microsoft/Nokia deal depends on a combination of execution and luck.

A photo taken on August 15, 2013 shows a Nokia Lumia 925 mobile telephone at the flagship store of Finnish mobile phone manufacturer Nokia in Helsinki. (MIKKO STIG/AFP/Getty Images)

The execution depends on whether they can find a way to increase their market share to become a solid number. For that, they'll need to offer plenty of smartphone choices at all price points, including low-cost phones for the developing world and the growing number of customers in Europe and the U.S. who are expected to buy their phones outright instead of depending on a carrier subsidy.

The other important piece to this puzzle is finding ways to increase the phone's ecosystem, which means convincing more developers to create apps for Windows phones. With Apple and Google's Android each hovering around a half-million apps and rising, these two juggernauts have a built-in advantage because, frankly, there is more that people can do with their devices. Also, Android and Apple apps automatically work on popular tablets and that's not the case with Windows -- at least not yet.

There is also the question of how this acquisition will affect other Windows phone makers. While it's theoretically possible that the synergy of Microsoft owning Nokia could spawn a resurgence of interest in other companies' Windows phone plans, it seems just as likely to lower the enthusiasm of the few companies currently in the marketplace. True, some incorrectly made the same predication after Google acquired Motorola last year, but there is a big difference between acquiring a company that was something of a bit player among the huge field of Android phone makers vs. acquiring practically the only serious hardware maker in the Windows phone marketplace.

Even though I don't take sides, I'm rooting for Microsoft/Nokia because I'd like to see more competition in the marketplace. It's not likely to come from Blackberry, so it's pretty much up to Microsoft at this point. As No. 3, Microsoft has to try harder both by innovating and by coming up with phones at a wide range of price points.